The present invention has for its object a socket contact for electrical contact devices, of the pin and socket type.
More precisely, the socket contact member of the invention is of the type in which, when the pin contact is not inserted, the areas of the socket contact intended to establish the contact with the pin contact are arranged at least approximately according to a family of straight generatrices of a hyperboloid of revolution of one branch. Said socket contact is achieved by means of permanent deformation by twisting according to a predetermined angle of a cylindrical hollow body or sleeve of suitable metal, provided with through slots arranged along its cylindrical surface and inclined with respect to the longitudinal axis of said cylindrical body, said twisting being directed in the sense of inclination of the slots. A socket contact of such type is disclosed for example in U.S. Pat. No. 4,447,108 in the name of the same inventor.
In socket contacts of that type there arises the problem (both due to standard rules and to functional requirements of the contact of obtaining the result that the electric contact between the socket and the pin does not take place beyond a predetermined length of insertion of the pin contact itself inside the bore of the socket contact. According to U.S. Pat. No. 4,447,108, said problem is solved by obtaining a zone of smaller thickness in the cylindrical sleeve which constitutes the socket contact and thus varying consequently the positioning of the zone of greatest reduction along the sleeve itself. More particularly said variation of the thickness is obtained by forming the sleeve in such a manner that it presents an outer conicity directed towards the inlet of the said sleeve. This prior solution of the problem, although satisfactory, presents some difficulties due to the necessity of obtaining an outer conicity of the sleeve, particularly in the case of reduced dimensions of the sleeve itself.
According to the present invention, the problem of the positioning of the zone of maximum reduction of the socket contact in proximity of the inlet of the socket contact itself is solved by providing, in a socket contact of the type above specified, a plurality of slots characterized by the fact that each has a lance-head or lanceolate shape, in which the bases of each slot are arranged in proximity to the annular inlet zone of the socket contact.